Image is not picked in imagepicker

I am trying to work with image picker where I will pick an image from gallery and it will change in aa given circle avatar when picked.

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
//import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:image_picker/image_picker.dart';

class AddDoctor extends StatefulWidget {
  @override
  State<AddDoctor> createState() => AddDoctorState();
}

class AddDoctorState extends State<AddDoctor> {
  File? _image;

  pickImage() async {
    final ImagePicker imagePicker = ImagePicker();

    final galleryFile =
        await imagePicker.pickImage(source: ImageSource.gallery) as File;

     if (galleryFile == null) {
       return galleryFile.readAsBytes();
     } else {
       print('No Image Selected');
     }

    setState(() {
      _image = galleryFile;
    });
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFFD9E4EE),
      appBar: AppBar(
        title: const Text('Add Doctor'),
        actions: [
          IconButton(
            icon: const Icon(Icons.menu),
            onPressed: () {},
          ),
        ],
      ),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: <Widget>[
          CircleAvatar(
            radius: 40,
            backgroundImage: _image != null ? FileImage(_image!) : null,
          ),
          const SizedBox(height: 10),
          ElevatedButton(
            onPressed: () {
              pickImage();
            },
            child: const Text('Upload Image'),
          ),
          const SizedBox(height: 10),
          
        ],
      ),
    );
  }

}

But in the debug console it's showing problem like Image not selected (which is set in my if condition at the beginning) and something like: Unhandled Exception: type 'XFile' is not a subtype of type 'File' in type cast

final galleryFile =
    await imagePicker.pickImage(source: ImageSource.gallery) as File;

here "As file" type cast is causing the problem because
The image picked is type of Object XFile and you're declaring it a File object so it's giving error type 'XFile' is not a subtype of type 'File' in type cast.
you can convert or use file path like this

final pickedXFile = await imagePicker.pickImage(source: ImageSource.gallery);

final galleryFile = File(pickedXFile.path);